Compute Rotation and Scale from Transform Object

[Ruts]

I did delete the rotX/Y/Z methods, that's why I didn't understand where the variable xyz came from and why it could get value = 0/1/2. I do understand how methods with there variables work. Sorry was confused.

On the other hand, I have been working with the euler_angle method for a while and now that I'm closely getting to a complete script I have noticed this method only partial works (for me?). Does it work for you guys? When I did draw shapes with a given rotation, the method didn't succeed to calculate the right angles for me so I did some research and made some changes. Here's the code I use:

	def self.rotation(trans)
		b = [trans.xaxis.to_a, trans.yaxis.to_a, trans.zaxis.to_a]
		m = b.transpose.flatten!
		if m[6] != 1 and m[6] != -1
			ry = -Math.asin(m[6])
			rx = Math.atan2(m[7]/Math.cos(ry),m[8]/Math.cos(ry))
			rz = Math.atan2(m[3]/Math.cos(ry),m[0]/Math.cos(ry))
		else
			rz = 0
			phipos = Math.atan2(m[1],m[2])
			phineg = Math.atan2(-m[1],-m[2])
			if m[6] == -1
				ry = Math;;PI/2
				rx = rz + phipos
			else
				ry = -Math;;PI/2
				rx = -rz + phineg
			end
		end   
	return [rx.radians,ry.radians,rz.radians]
	end	

First I found this document (page 5) that explains the calculations the way you do it. But it seems that you miss little pieces of code to make it complete.

When I did calculate the angles it yet didn't calculate the right angles. So I did try some things and found out that the angles that were calculated represent the transpose matrix of the rotation that I need. So I fixed this by transposing the rotation matrix before the calculations.

With these changes this piece of code does calculate the right angles. Did your code work for you?

[Dan Rathbun]

You realize that this topic thread is like 4 and 1/2 years old ?

[Ruts]

@dan rathbun said:

You realize that this topic thread is like 4 and 1/2 years old ?

Yes, I have seen it. That does not mean that people can't come here and look for code that works? That's how I landed here. I was looking for some code that could convert the rotation matrix to euler angles. I found out that this code didn't work for me, so I did correct it and now I share it here just in case people experience the same problem as me. I'm just excited that I finally can contribute a little instead of always asking things!

Nothing wrong with that, right?

[Dan Rathbun]

@ruts said:

@dan rathbun said:

You realize that this topic thread is like 4 and 1/2 years old ?

Yes, I have seen it. ... Nothing wrong with that, right?

I was referring to your asking questions of original posters, who might not remember, or might not even have been active here for some time.

[Jernej Vidmar]

Hello transformation gurus!

just to double check the euler_angle(xyz=[]) method ... is the condition:

if m[6] != 1 and m[6]!= 1

at the beginning correct? Why double checking the same variable against the same value? Or is it meant to be:

if m[6] != 1 and m[6]!= -1

?

Cheers,
Jernej

[TIG]

An olde typo - use 1 for the second test...